I think you will find it is just a clear laquer that lots of old manufacturers used to make things all glossy. A wipe over with a thinners or metho rag will remove most of it and it will take on an even matt sheen usually.
You often see the same things under the bonnet of ur car a few yrs after you have bought it from a used car yard. They do the same a glossy ultra thin cosmetic gloss for a better presentation.
Jack.